A counterflow diffusion flame study of branched octane isomers

Subram Sarathy*, Ulrich Niemann, Coleman Yeung, Ryan Gehmlich, Charles K. Westbrook, Max Plomer, Zhaoyu Luo, Marco Mehl, William J. Pitz, Kalyanasundaram Seshadri, Murray J. Thomson, Tianfeng Lu

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

35 Scopus citations


Conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels typically contain a high concentration of lightly methylated iso-alkanes. However, until recently little work has been done on this important class of hydrocarbon components. In order to better understand the combustion characteristics of real fuels, this study presents new experimental data for 3-methylheptane and 2,5-dimethylhexane in counterflow diffusion flames. This new dataset includes flame ignition, extinction, and speciation profiles. The high temperature oxidation of these fuels has been modeled using an extended transport database and a high temperature skeletal chemical kinetic model. The skeletal model is generated from a detailed model reduced using the directed relation graph with expert knowledge (DRG-X) methodology. The proposed skeletal model contains sufficient chemical fidelity to accurately predict the experimental speciation data in flames. The predictions are compared to elucidate the effects of number and location of the methyl substitutions. The location is found to have little effect on ignition and extinction in these counterflow diffusion flames. However, increasing the number of methyl substitutions was found to inhibit ignition and promote extinction. Chemical kinetic modelling simulations were used to correlate a fuel's extinction propensity with its ability to populate the H radical concentration. Species composition measurements indicate that the location and number of methyl substitutions was found to particularly affect the amount and type of alkenes observed. Published by Elsevier Inc. on behalf of The Combustion Institute.

Original languageEnglish (US)
Pages (from-to)1015-1023
Number of pages9
JournalProceedings of the Combustion Institute
Issue number1
StatePublished - Jan 1 2013


  • 2,5-Dimethylhexane
  • 3-Methylheptane
  • Counterflow diffusion flame
  • Extinction
  • Ignition

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry


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